This application is based on application No. 11-328129 filed in Japan on Nov. 18, 1999, the contents of which is hereby incorporated herein by reference.
1. Field of the Invention
The present invention pertains to an image processing device that processes digital image data, and more particularly to an image processing device that changes the magnification of images.
2. Description of the Related Art
When performing image formation, the magnification of the input image may be electrically changed in accordance with the magnification ratio in an image processing device. When the image is enlarged, the pixel data is inflated. For example, when the magnification is 2.0, the same pixel data is output twice in succession. When this is done, the image deteriorates due to jaggedness. When the image is reduced, the pixel data is thinned out. For example, where the magnification is 0.5, the pixel data is output for every other pixel. When this is done, the image deteriorates due to data loss. As a result, in order to prevent deterioration in the quality of the image, correction of the image data is performed for both enlargement and reduction. This correction is termed xe2x80x98interpolationxe2x80x99 below.
In a conventional image processing device, the magnification processing circuit has (i) a reducing interpolation unit that carries out interpolation of the input pixel data when reduction is to be performed, (ii) a reduction/enlargement unit that carries out thinning out or inflation of the pixels, and (iii) an enlarging interpolation unit that carries out interpolation of the input pixel data when enlargement is to be performed. The reducing interpolation unit, the reduction/enlargement unit and the enlarging interpolation unit are controlled based on the magnification information supplied by the CPU.
In the case of reduction, in order to prevent such processing from causing a deterioration in image quality, after interpolation of the pixel data is carried out by the reducing interpolation unit in accordance with the reduction ratio, the interpolated pixel data is thinned out by the reduction/enlargement unit and the image is reduced. In the case of enlargement, after the pixel data is inflated by the reduction/enlargement unit in accordance with the magnification and the image is enlarged, interpolation of the inflated pixel data is carried out by the enlarging interpolation unit in order to prevent the enlargement processing from causing deterioration of the image quality.
As described above, the conventional magnification processing circuit requires separate and independent interpolation circuits for enlargement and reduction in order to prevent image deterioration after the magnification processing. As a result, the size of the circuitry increases, thereby increasing the cost of the device.
An object of the present invention is to provide a small magnification processing circuit.
In order to achieve this and other objects, an image processing device comprising a first aspect of the present invention comprises a device that has a variable circuit construction and includes (i) a correction unit that corrects for image deterioration caused by changes in image magnification, (ii) a reduction/enlargement unit that, based on the magnification, thins out the pixel data when reduction is being performed or carries out inflation of the pixel data when enlargement is being performed, and (iii) a controller that changes the operation of the correction unit in response to the magnification.
An image processing device comprising a second aspect of the present invention includes (i) a correction unit comprising a device that has a variable circuit construction so that it functions as a reduction correction circuit when reduction is being performed and functions as an enlargement correction circuit when enlargement is being performed, (ii) a reduction/enlargement unit that thins out the pixel data when reduction is being performed and inflates the pixel data when enlargement is being performed, and (iii) a controller that changes the operation of the correction unit so that it functions as a reduction correction circuit when reduction is being performed and functions as an enlargement correction circuit when enlargement is being performed.
Embodiments of the present invention also may have the characteristics described below.
The image processing device may have a first selector that outputs input pixel data to the reduction/enlargement unit when enlargement is being performed, and outputs pixel data from the correction unit to the reduction/enlargement unit when reduction is being performed, a second selector that outputs pixel data from the reduction/enlargement unit to the correction unit when enlargement is being performed, and outputs input pixel data to the correction unit when reduction is being performed, and a third selector that outputs pixel data from the correction unit when enlargement is being performed, and outputs pixel data from the reduction/enlargement unit when reduction is being performed.
The controller may change the operation of the correction unit so that when reduction is being performed it will function as a reduction correction circuit to correct image deterioration caused by the thinning out of the pixel data, and when enlargement is being performed it will function as an enlargement correction circuit to correct image deterioration caused by inflation of the pixel data.
The reduction correction circuit may comprise a filter circuit in which the parameters are changed in accordance with the reduction ratio.
The enlargement correction circuit may have multiple types of filter circuits, and the filter used may be selected in accordance with the enlargement ratio.
The correction unit may comprise a filter circuit in which the parameters may be changed in accordance with the magnification.
The correction unit may be comprised of a field programmable gate array.